1. Field of the Invention
The present invention relates generally to optical data transmission and more particularly to a transmitter which can selectively transmit data in either one of two operating modes: a low-power light-emitting diode mode and a high-power laser diode mode.
2. Description of the Related Art
Presently, components of some computer systems transmit data over fiber optic links. Optical data transmission networks in use today commonly employ a light-emitting diode (LED) transmitter coupled by a fiber optic link to a PIN photodetector receiver. Another optical data transmission network in use now, which will become more prevalent in the future, uses an injection laser diode transmitter.
The power output of an injection laser diode transmitter is considerably higher than the power output of a light-emitting diode; for example, the power output of a laser diode is about 1 milliwatt as compared with a power output for a light-emitting diode of about 0.02 milliwatts. The output of a laser diode transmitter would saturate a receiver designed for use with a light-emitting diode transmitter. While it is possible to provide a different transmitter matched to the intended receiver, the direct and indirect costs of such an approach are high.